1. Field of the Invention
This invention relates to devices for introducing a water soluble compound, such as a pesticide or fertilizer, into the vascular system of plants.
2. Description of the Prior Art
The injection of nutrients, pesticides and dyes into the vascular system of trees and plants has long been known in the art, as evidenced by the issuance of more than a dozen U.S. patents related methods and apparatus since the beginning of the twentieth century. For example, U.S. Pat. No. 952,245 to Levi S. Gardner discloses a process for coloring the wood of living trees by injecting dyes into their vascular systems. U.S. Pat. No. 2,044,063 to Arnold V. Dahlberg, is an example of a process for fertilizing trees and shrubs which bypasses the natural root system by introducing a nutrient solution directly into the cambium layer. More recent patents include U.S. Pat. No. 3,286,401 to James J. Mauget for a pressurized plant injection device and U.S. Pat. No. 4,989,366 to Terry A. DeVlieger for a gravity-feed fluid injection device for trees.
During the past decade, the world economy has experienced explosive economic growth. That growth has resulted in greatly increased demand for paper and lumber. Increased demand and more restrictive logging directives recently promulgated by the U.S. Forest Service have resulted in a doubling of the price of lumber during the same period. Sadly, at this time of increasing demand for timber, whole forests often die from insect infestations. While gypsy moths destroy hardwood trees, bark beetles lay waste to stands of Douglas firs. Annual losses to insect pests total in the billions of dollars.
The spraying of insecticides on forests has several major drawbacks. First, the insecticides are generally non-selective. Thus, both harmful and beneficial insects are killed. Second, aerial spraying of forests is in mountainous regions is quite hazardous. Third, pesticides are expensive, and aerial spraying coats everything, along with the trees. Fourth, much of the sprayed liquid ends up in streams and rivers, with deleterious consequences for animal life living on land and in water.
Though many of the existing injection methods and apparatus would work for injecting pesticides into the vascular tissue of trees, the known methods and devices are either too complex or too expensive to be used to treat entire forests. What is needed is a simple, inexpensive device which can be rapidly installed in the trunks of trees and which can be used to distribute insecticide throughout the vascular system of the tree so that insect pests that feed on parts of the tree will die.
The present invention includes a spike having a hollow body which provides a storage chamber for a water soluble compound such as a pesticide, fungicide, fertilizer, or any other aqueous solution used for the intravascular treatment of trees. The spike has a generally pointed end which can be driven into the trunk of tree. The hollow body is equipped with bleed apertures near the pointed end, so that when the spike is driven into the trunk of a tree, the storage chamber is coupled to the vascular system thereof. The spike is supplied with a resilient sheath that seals the bleed apertures during shipping and handling. As the spike is driven into a tree trunk, the sheath is peeled off the body, thereby exposing the bleed apertures to the tree""s vascular tissue and forming a gasket between the spike body and the aperture created by driving the spike into the trunk.
For a preferred embodiment of the invention, the spike includes a generally elongated, hollow body fabricated from a section of steel tubing. A hammer-drivable head, also made of steel, is welded or adhesively bonded to one end. The head may be either stamped, cast or machined. A pointed end piece, which may be either machined or cast, is welded or adhesively bonded to the opposite end. Bleed apertures are made in the tube wall near the pointed end and the spike is dipped in a solvated liquid polymeric compound. Once the solvent has evaporated, the polymeric compound becomes the resilient sheath, which seals the bleed apertures. When so assembled, a sealed chamber is formed within the tubing between the hammer drivable head and the point. The chamber can be most easily filled with a water soluble solution either by adhesively installing the hammer-drivable head last or by providing an aperture within the head which can be plugged after filling the chamber. For a preferred method of use, the spike is driven into the trunk near the base of the tree until the bleed apertures are positioned within the sapwood. In addition to sealing the fertilizer and/or pesticide containing solution, the sheath serves as a gasket once the spike is driven into a tree trunk, forming a seal which helps to prevent leaks of the solution to the exterior surface of the tree trunk.
If it is deemed important that the wood of the tree not be stained, the spike may be fabricated from stainless steel or heat-treated aluminum.
Alternative embodiments of the invention are also contemplated. For example, the spike may be injection molded from polymeric materials such as polyesters, acrylics, and epoxies, which are reinforced with structural fibers formed from glass, carbon, metal, or similar materials. As an ecological measure, the tree spike may even be cast from fiber-reinforced concrete. For tree spikes manufactured from polymeric materials or fiber-reinforced concrete, it may be preferable to drill, in the tree trunk, a hole having a diameter slightly smaller than that of the spike, so that an interference fit may be achieved without utilizing the spike to create the hole.
In order to rapidly treat large numbers of trees, the spike may be driven into tree trunks using a gun powered by pressurized air or explosive charges.